A number of fluid recovery systems have been developed for draining fluid, such as air and/or blood, from a patient. An example of such a fluid recovery system is a chest drainage system. Chest drainage systems are intended to remove fluid from the pleural space or the mediastinal cavity and to restore the sub-atmospheric pressure that is normally present in the pleural space. The systems are usually adapted to allow suction to be applied to the chest cavity to facilitate, among other things, the removal of fluid from the pleural space. Once the fluid has been removed, the pleural cavity is allowed to heal and the normal subatmospheric condition of the pleural space is restored.
Over the years, various drainage systems have been proposed. For example, U.S. Pat. No. 4,605,400 discloses a surgical draining apparatus having an air leak indicating means for indicating the directional flow of any gases through a passageway and optionally the qualitative quantity of these gases. The air leak indicating means includes a liquid trap which is visible through the container. Thus as any gases flow therethrough, bubbles are formed which serve as visible indicators of such a flow and of a patient air leak. No bubbling through the liquid indicates a proper operation of the drainage apparatus. However, continuous bubbling through the liquid indicates either an air leak in the connections or an air leak in the pleural cavity of the patient. The gases pass through an aperture which is uppermost in a slanted divider member. However, as the flow of gases increases, the gases additionally flow through succeeding lower apertures along the length of the divider member. Thus, the lowermost of the apertures through which the gases bubble indicates the volume of flow through the air leak indicating means. Suitable indicia are provided on the outside of the drainage apparatus to indicate this to the user.
U.S. Pat. No. 4,654,029 discloses an electronic drainage system including a combination of electronic and mechanical components for measuring and displaying values for air flow, suction, patient negativity and maximum negativity. A patient air flow transducer is located to measure the flow rate of air and other gases in a conduit from the patient. A signal processor is electrically connected to the transducer to convert the signal from the transducer to a form needed by an air flow display. The readout of the display can be provided in units of liters per minute. A patient negativity transducer is also provided in the air conduit to measure the negative pressure in the pleural space. Since larger levels of negativity may occur while an attendant monitoring the system is away from the patient, it may be useful for the physician to know what maximum level of negative pressure was actually attained (e.g., if the tube inserted into the pleural space becomes clogged with blood clots, damaged tissue or the like). In order to clear a blockage, the attendant “milks” the tube in an attempt to reopen it, however, this procedure often causes high values of momentary negativity on the patient. In order to determine that this has happened and to what extent, a maximum negativity hold device is electrically connected to the signal processor and is so devised as to record and store negativity values up to the level permitted by an excessive negativity release or safety valve. The stored value is displayed on a display function. Also, a weight transducer is electronically connected with a fluid collection chamber for weighing the fluid in the chamber as a function of time. The weight transducer and an associated processor and display, enable the measurement and recording of the parameter fluid versus time.
U.S. Pat. No. 4,740,202 relates to a portable suction system in which the vacuum for suction purposes is provided by evacuating a rigid plastic chamber connected to a vacuum pump. A disposable bag is affixed to a suction port on the chamber's cap. In operation, the rigid chamber is evacuated by the vacuum pump, thus drawing air and fluids through a suction tip into a suction port and into the flexible collection bag where the liquids are retained for collection.
In U.S. Pat. No. 6,352,525, an entire drainage system is made completely portable by combining a vacuum pump, a power source, a vacuum chamber, and a collection unit into a single unit. A vacuum chamber, vacuum pump housing, and collection reservoir are removably connected to the chest tube drainage system, each component of the drainage system being generally disposable. A flow meter is interposed between the vacuum chamber and the vacuum pump housing to indicate the amount of air flow. The flow meter includes a flow meter tube within which a floating ball rests. The diameter of the floating ball, the weight of the floating ball, and the inner diameter of the flow meter tube are configured such that the floating ball rests substantially near the bottom of the flow meter tube when there is little or no leak from a patient's lung(s), and such that the floating ball rests substantially near the top of the flow meter tube when a substantial leak exists in a patient's lung(s). In the context of a patient recovering from lung-related surgery, the flow meter indicates an amount of air leak from the patient's lung(s). The amount of air flow through a chest tube is indicated by the flow meter, and a practitioner may adjust a potentiometer until flow characteristics indicated by the flow meter correspond favorably to an amount of air leak which may persist for some time at a lung.
U.S. Pat. No. 7,207,946 discloses a method of providing a signal indicating information related to air evacuation from a chest cavity. An air escapement conduit is inserted into an air evacuation pathway between the chest cavity and a vacuum source, allowing an air flow in response to a pressure differential, generating a signal related to the air flow, and indicating air evacuation information in response to the signal. The air escapement conduit includes a bubble chamber having a fluid disposed between an inlet port and an outlet port so that air flowing between the ports flows through the fluid and forms bubbles. Bubbles in the fluid are counted and a bubble detection signal related to counted bubbles is generated. A difference in air pressure between the ports is detected, and a signal related to the difference is generated. A flash of light provided by a light emitting diode indicates when the air evacuated per selected unit of time exceeds a predetermined level. Data representative of the signal may be stored.
Despite many developments in the field of fluid drainage, however, there remains a need for improved drainage systems, particularly improved chest drainage systems.